In the past, the outside housings for large machines used fasteners to attach a panel to the frame. The panels that form the housing have predominantly been made of metal. Advantageously, the metal panels provide the needed protection against EMI for some machines such as a computer. In addition, welded and painted metal sheets have also been used since the tooling costs associated with manufacturing machines with metal panels is low. However, use of metal sheets requires many manufacturing steps including forming the sheet metal, making fastener openings in the sheet metal and painting the sheet metal. The metal sheets are fastened with fasteners which uses up manufacturing time and field time for upgrades or repair. Metal sheets are also subject to dents, scratches and scrapes.
More recently, housings have been made of plastic. In a computer system having shielded components, some have been provided with plastic panels for an outside housing. These plastic panels are still attached with separate fasteners and have the advantage of being more resistant to scratches or dents.
Any panel or cover that is attached using fasteners requires extra parts during the manufacturing of the computer. A separate bin of fasteners must be kept on hand and be kept in stock so that the computer housing can be finally assembled. In addition to keeping a bin of fasteners for the final assembly, when using plastic panels other parts must also be kept on hand. The plastic panels attached with fasteners require the installation of a metal boss around the openings in the plastic panel through which the fasteners will pass. Thus, for a plastic panel, even more parts are required to manufacture the computer housing.
In addition to having extra parts, fastening a panel with fasteners, such a small sheet metal screws, requires a fair amount of time. At a minimum, each panel requires at least four such fasteners and more than likely a minimum of eight. Screwing in the fasteners takes time. It also may require specialized machinery such as mechanical screwdrivers but these are generally on a production line already. The mechanical screwdrivers are also faster.
With a formed-sheet plastic panel, additional manufacturing steps for adding bosses to the openings are required. This also adds to the manufacturing process and requires additional parts.
After manufacture, field engineers will generally be called on to either service the machine or upgrade the machine. When fasteners are used to attach machine covers to a housing, the field engineer must remove a number of screws or fasteners to gain access to the parts necessary to fix or upgrade the machine. The screws must also be replaced. This takes valuable field time.
The manufacturing world always has a need for parts and processes that replace multiple parts since this produces a net reduction in the number of parts needed during manufacture. If fasteners can be eliminated, this not only simplifies the manufacturing process but also makes upgrades and servicing a unit in the field much easier. Manufacturers are also looking for ways to make manufacturing lines safer for their workers.